Post by LSDeep on Apr 16, 2006 10:26:42 GMT -5
Living in the tropics is great but there are a few stinging creatures to be aware of. Everyone has heard of fire coral but how many know that it is not actually a hard coral but rather a stinging hydroid? And did you know that a coral cut can be rapidly fatal on occasion? But let's take a step back…
The phylum cnidaria (silent 'c'), previously known as coelenterates, contains 4 classes of interest from a stinging viewpoint:
* Hydrozoa - includes plume -like hydroids, firecorals and Portugese Man 0'War.
* Scyphozoa - certain jellyfish.
* Cubozoa - box jellyfish such as Chironex fleckeri and Irukandji.
* Anthozoa - Anemones, hard and soft corals, sea whips and sea fans.
This discussion will focus on the hydrozoa and anthozoa.
The hydrozoa occur in fresh and salt water, and may be solitary or colonial. Most local divers would have felt the slight sting from the brown sticky fern-like "plants" under rock ledges. This sticky feel is due to the presence of stinging cells or nematocysts which discharge on contact, firing a small harpoon into your skin and sometimes injecting a venom. Nematocyts are common to most (?all) cnidaria. Stings from the feather hydroids will usually produce to an irritating pimply rash. Care must be taken not to allow this to become infected especially in the tropics, but the rash will usually settle within days and not produce permanent scars. Ice packs often give good symptom relief.
Fire Corals (millepora sp.) are found in many parts of the world. They resemble a smooth rubbery branching hard coral and appear a quite innocuous green/brown colour. Contact produces immediate burning pain which may be intense. Within 24hrs a lumpy rash appears which may become pustular then break down to open sores. The wound may last for weeks. No deaths have been reported. Treatment is to clean the area then apply ice packs for symptom relief.
Anthozoa including the hard corals may also contain stinging nematocysts. However a wound related purely to these stinging cells is uncommon since the coral usually abrades the skin as well. Coral cuts are very common and may lead to chronic wound healing problems or dangerous infections. When the skin is cut, foreign matter (proteins, calcium coral skeleton, marine and terrestrial microorganisms) are deposited into the tissues. Within hours, if neglected, an even trivial wound may become red, painful and itchy. Local lymph glands may enlarge. If bacterial infection ensues, the victim may begin to feel generally unwell. The most important first aid treatment for even mild coral cuts is to gently scrub the wound with fresh water containing a mild antiseptic. The more thoroughly the wound is cleaned, the less the chances of a problem developing. Don't be afraid to scrub right into the depths of the wound and create a little fresh bleeding. Any deeper wounds should be seen by a doctor to consider cleaning under anaesthetic. Tetanus vaccination may be required.
Antibiotics may be required for infected wounds. A family of bacteria called vibrionaceae can be found in some coral and fish spine wounds, and can cause rapidly fatal infections in affected patients. This tends to occur in individuals with other medical problems like diabetes or kidney disease. Luckily, it is more often the staph. and strep. bacteria that are the problem and these infections are less likely to be life threatening. If no allergies are present, then a course of Bactrim, Augmentin or Doxycline is usually effective in infected wounds, However the importance of adequate wound cleaning cannot be over emphasised.
Ref: Venomous & Poisonous Marine Animals, UNSW Press, 1996.
The phylum cnidaria (silent 'c'), previously known as coelenterates, contains 4 classes of interest from a stinging viewpoint:
* Hydrozoa - includes plume -like hydroids, firecorals and Portugese Man 0'War.
* Scyphozoa - certain jellyfish.
* Cubozoa - box jellyfish such as Chironex fleckeri and Irukandji.
* Anthozoa - Anemones, hard and soft corals, sea whips and sea fans.
This discussion will focus on the hydrozoa and anthozoa.
The hydrozoa occur in fresh and salt water, and may be solitary or colonial. Most local divers would have felt the slight sting from the brown sticky fern-like "plants" under rock ledges. This sticky feel is due to the presence of stinging cells or nematocysts which discharge on contact, firing a small harpoon into your skin and sometimes injecting a venom. Nematocyts are common to most (?all) cnidaria. Stings from the feather hydroids will usually produce to an irritating pimply rash. Care must be taken not to allow this to become infected especially in the tropics, but the rash will usually settle within days and not produce permanent scars. Ice packs often give good symptom relief.
Fire Corals (millepora sp.) are found in many parts of the world. They resemble a smooth rubbery branching hard coral and appear a quite innocuous green/brown colour. Contact produces immediate burning pain which may be intense. Within 24hrs a lumpy rash appears which may become pustular then break down to open sores. The wound may last for weeks. No deaths have been reported. Treatment is to clean the area then apply ice packs for symptom relief.
Anthozoa including the hard corals may also contain stinging nematocysts. However a wound related purely to these stinging cells is uncommon since the coral usually abrades the skin as well. Coral cuts are very common and may lead to chronic wound healing problems or dangerous infections. When the skin is cut, foreign matter (proteins, calcium coral skeleton, marine and terrestrial microorganisms) are deposited into the tissues. Within hours, if neglected, an even trivial wound may become red, painful and itchy. Local lymph glands may enlarge. If bacterial infection ensues, the victim may begin to feel generally unwell. The most important first aid treatment for even mild coral cuts is to gently scrub the wound with fresh water containing a mild antiseptic. The more thoroughly the wound is cleaned, the less the chances of a problem developing. Don't be afraid to scrub right into the depths of the wound and create a little fresh bleeding. Any deeper wounds should be seen by a doctor to consider cleaning under anaesthetic. Tetanus vaccination may be required.
Antibiotics may be required for infected wounds. A family of bacteria called vibrionaceae can be found in some coral and fish spine wounds, and can cause rapidly fatal infections in affected patients. This tends to occur in individuals with other medical problems like diabetes or kidney disease. Luckily, it is more often the staph. and strep. bacteria that are the problem and these infections are less likely to be life threatening. If no allergies are present, then a course of Bactrim, Augmentin or Doxycline is usually effective in infected wounds, However the importance of adequate wound cleaning cannot be over emphasised.
Ref: Venomous & Poisonous Marine Animals, UNSW Press, 1996.